1. Field of the Invention
This application is directed to a single catalyst system and process for using same in a single stage operation for hydrodewaxing and hydrotreating various petroleum residua.
2. Description of the Prior Art
It is well known that many if not most petroleum base stocks contain contaminants, as for example sulfur, nitrogen and metals. It is desirable particularly if these feedstocks are to be further processed that the contaminants be removed. This is an operation usually requiring use of a catalyst.
It has been conventional in the art to effect sulfur removal from hydrocarbon stocks by subjecting them to treatment with hydrogen at elevated temperature and pressure while in contact with a catalyst containing hydrogenating components. Typically the hydrogenating components of such prior art catalysts are Group VI-B or Group VIII metals, or their oxides or sulfides. These hydrogenating components may be supported on a variety of well-known carriers, for example, alumina, kieselguhr, zeolitic molecular sieves and other materials having high surface areas; U.S. Pat. Nos. 4,080,296, 3,546,103 teaches hydrodesulfurization with a catalyst of cobalt and molybdenum on an alumina base. U.S. Pat. No. 3,755,145 describes a process for preparing lube oils characterized by low pour points which utilizes a catalyst mixture comprising hydrogenation components, a conventional cracking catalyst which can be either crystalline or amorphous and a crystalline aluminosilicate of the ZSM-5 type.
U.S. Pat. No. 3,894,938 relates to the catalytic dewaxing and desulfurization of high pour point, high sulfur gas oils to lower their sulfur content by contacting such an oil first with a ZSM-5 type zeolite hydrodewaxing catalyst which may contain a hydrogenation/dehydrogenation component in the presence or absence of added hydrogen followed by conventional hydrodesulfurization processing of the dewaxed intermediate.
Copending application Ser. No. 310,550, filed Oct. 13, 1981, discloses and claims a single stage operation for hydrotreating and hydrodewaxing of petroleum residua using a dual catalyst system, i.e. a hydrodesulfurization catalyst combined with a metal-containing ZSM-5 hydrodewaxing catalyst.
However, neither the prior art mentioned above nor said copending application have combined, in a single stage operation, the hydrodewaxing and hydrotreating of petroleum resids using a single catalyst system.